This invention relates generally to valve gated injection molding, and more particularly to a system having an easily replaceable rocker arm assembly.
In many valve gated injection molding systems, reciprocable actuating mechanism is connected directly to the head of each valve pin. However, in some situations, this arrangement is not convenient or even possible. Therefore, as is well known, a pivotable rocker arm is frequently used to connect the head of the valve pin to remotely located actuating mechanism. Examples of this type of structure are described in U.S. Pat. No. 4,013,393 to Gellert entitled "Valve-Gated Injection Molding Mechanism" which issued Mar. 22, 1977, U.S. Pat. No. 4,026,518 to Gellert entitled "Bushing Seal for Valve-Gated Injection Mold", which issued May 31, 1977 and U.S. Pat. No. 4,222,733 to Mold-Masters Limited entitled "Injection Molding Flow Control Mechanism" which issued Sept. 16, 1980. As mentioned in these patents, it will be appreciated that rocker arm wear due to their repetitive pivotal action is an important factor in providing a system which does not require unacceptable maintenance and down time.
In order to reach the valve pin, the rocker arm is mounted in the mold core or backplate. In these previous systems, in order to repair or replace the rocker arm due to malfunction or routine maintenance, it is necessary to disassemble a portion of the mold. This has the disadvantages of being relatively costly and requiring considerable system down time.